In accordance with hair composition terminology, the term "silicone oil" is used herein to designate water-insoluble silicone polymers which are applied to hair to improve its feel or appearance. Silicone oils can provide the hair with a silky, lubricious feel. They can also provide a lusterization effect. These results are obtained by coating hair strands with thin films of silicone oil.
Since silicone oils are substantially water-insoluble, after application to the hair they tend to remain thereon despite rinsing with water. Silicone oil can therefore be applied in a shampoo, or in a hair conditioner applied after shampooing, and then followed by water-rinsing.
The two most common types of hair conditioning silicone oils are referred to in the International Cosmetic Ingredient Dictionary (CTFA) as "dimethicone" and "dimethiconol". Dimethicone is defined as a mixture of fully methylated linear siloxane polymers end blocked with trimethylsiloxy units. Dimethiconol is a dimethyl silicone polymer terminated with hydroxyl groups. Such hair conditioning silicone oils are relatively non-volatile liquids. Dimethicone and dimethiconol silicone oils are obtainable from commercial sources in the United States and other countries.
Since silicone oils have very limited solubility in aqueous products, they are usually applied in the form of aqueous emulsions or dispersions. For example, in a water-based shampoo or hair conditioner, the silicone oil may be dispersed with the aid of an emulsifying agent, and the dispersion or emulsion may be stabilized by the inclusion of thickeners.
Cationic hair conditioning agents are also commonly used in hair treating compositions. Typically, cationic hair conditioning agents contain one or more cationic quaternary nitrogen groups, and one or more hydrophobic long chain aliphatic or silicone polymer. The cationic group can provide a degree of substantivity between the conditioning agent and hair. The long chain hydrophobic groups, which are derived from long chain fatty acids, or are silicone polymers, can provide hair conditioning functions.
Silicone oils have been disclosed as ingredients of water-based shampoos which also contain a quaternary nitrogen-containing conditioning agent and an anionic surfactant. U.S. Pat. Nos. 4,704,272, 3,964,500, and 5,034,218 are illustrative of such formulations. Silicone oils are also disclosed as ingredients of after-shampoo hair conditioning emulsions. (See, for example, U.S. Pat. No. 4,387,090.)
Silicone co-polymers, designated by the CTFA as "dimethicone copolyol" are also used in hair conditioner compositions. The cosmetic Dictionary definition is: a polymer of dimethylpolysiloxane with polyoxyethylene and/or polyoxypropylene side chains. These copolymers are not silicone oils since they are water-soluble.
Cationic silicone polymers have been proposed for use in hair conditioning compositions, as disclosed in U.S. Pat. Nos. 4,529,586, 4,597,962 and 4,839,167. U.S. Pat. No. 4,529,586 describes a hair conditioning composition in which one of the ingredients is an amino functional silicone polymer. The composition also contains a cationic surfactant-emulsifier and a cationic polymer.
U.S. Pat. No. 4,597,962 discloses compositions containing cationic silicone polymers of specified structural formulas. The compositions also include a cationic surface-active agent and a water-soluble diquaternary polyammonium compound.
U.S. Pat. No. 4,839,167 discloses an emulsion-type hair cosmetic containing a dimethylpolysiloxane polyoxyalkylene copolymer. The compositions also contain dimethicone copolyol, and the compositions are formulated from mixtures of water and ethanol. In the compositions of the previously cited patents (U.S. Pat. Nos. 4,529,586 and 4,597,962) water is used as the carrier.